This invention relates to a system that uses ultraviolet light to kill bacteria in a portion or all of a refrigerator, in order to inhibit food spoilage.
Although refrigerators by their relatively low temperature slow the bacteria-induced spoilage of food, this only delays the inevitable food spoilage problem. Typically, within a matter of days bacteria on or in the food spoils the food. And, even if the food is still edible, the presence of bacteria can lead to potential health problems.
It has been known for some time that ultraviolet light retards food spoilage. See, for example, U.S. Pat. No. 4,121,107: Apparatus for automatic low-bacteria to aseptic filling and packing of foodstuffs. However, this patent relates only to food packaging, and does not address issues concerning protection of foods once packaging has been opened, or more generally to protection of foods that are kept in a refrigerator.
The invention uses an ultraviolet light in a refrigerator to diminish the amount of organisms that may lead to spoilage of foods. When the refrigerator door is closed, an ultraviolet (UV) light is turned on, possibly only for a short, predetermined time. There could be a separate compartment in the refrigerator for this, so that only foods placed in this compartment are exposed to UV light. The light needs to be on only long enough to accomplish the killing action of UV light.
There could be up to 7 safety mechanisms for preventing inadvertent exposure of a person to the UV light.
1) the light switch on the door is used to determine positive closure of the door.
2) a time delay after door closure to increase likelihood that door is completely closed.
3) a light sensor prevents the UV light from turning on if there is not total darkness in the refrigerator, which may be if the door switch is defective or if the door is left partially open.
4) if a separate compartment is employed, it could have its own door with its own switch in addition to the main door.
5) A message regarding possible malfunction of the door interlock could be written on the inside of the refrigerator wall in a fluorescent ink which is only visible or distinguishable from the background when UV light is shining on it.
6) A short range IR movement sensor pointing towards the front of the refrigerator could be employed to extend the time delay until no one is standing in front of the refrigerator any more.
7) The UV light could be wired in parallel with a blue light which would be visible to the human eye and would alert someone to malfunction, just as propane gas is mixed with a substance that gives it the characteristic odor to alert people of gas leaks.
This invention features a system for retarding food spoilage in a refrigerator, comprising: an ultraviolet light mounted within the refrigerator; and means for turning on the light for at least a predetermined time only after the refrigerator door is shut, to bathe foodstuffs in at least a portion of the refrigerator with UV light for a sufficient time to kill at least some of the organisms on the foodstuffs.
The means for turning on the light may be responsive to the light switch on the door, so that the UV light is not turned on until positive closure of the door. The system may further include a time delay after door closure for the means for turning on, to increase the likelihood that the door is completely closed. The system may also include a light sensor to prevent the UV light from turning on if there isn""t total darkness in the refrigerator, to prevent the UV light from coming on if the door switch is defective or if the door is left partially open.
The system may still further include a separate compartment in the refrigerator holding the UV light. The separate compartment may have its own door with its own switch to which the means for turning on is responsive. The system may further include a message regarding possible malfunction of the door interlock on the inside of the refrigerator wall in a fluorescent ink which is only visible or distinguishable from the background when UV light is shining on it. The system may still further include a short range IR movement sensor pointing towards the front of the refrigerator, to extend the time delay until it is more likely that no one is standing in front of the refrigerator. The UV light may be wired in parallel with a visible light, to alert to malfunction.